B2: Organisation Flashcards
What does it mean if a cell is specialised?
they are adapted for a particular purpose
When do most animal cells differentiate?
in the early stages of development
When can most plant cells differentiate?
throughout their life
What happens as a cell differentiates?
-it may change shape
-different sub-cellular structures develop to enable it to carry out a specific function
How are sperm cells adapted to carry out their function?
they have many mitochondria (provide energy), they have an acrosome (contains enzymes to penetrate the outer layer of the egg), the nucleus only contains one set of genetic material and they have a tail
How is a root hair cell adapted for its function?
lots of mitochondria for active transport, large surface area to absorb water and minerals
What is a tissue?
a group of cells with a similar structure and function, which all work together to do a job
What is an organ?
a group of different tissues which all work together to perform a specific job
What is the role of muscle tissue in the stomach?
contracts to churn the contents
What is the role of glandular tissue in the stomach?
produce digestive juices
What is the role of epithelial tissue in the stomach?
cover the outside and inside of the stomach
What is an organ system?
a group of organs working together to do a particular job e.g the digestive system
What is an enzyme?
a biological catalyst; they speed up chemical reactions in living organisms
Name some of the properties of an enzyme.
-they are all large proteins
-there is a space within the protein molecule called the active site
-each enzyme catalyses a specific reaction
-they work best at a specific temperature and pH called the optimum
What is the ‘lock and key theory’?
a model used to explain how enzymes work
Describe the ‘lock and key theory’.
the chemical that reacts is called the substrate and it fits into the enzyme’s active site
What is denaturing?
when the shape of an enzyme is changed (by excessive temperature or pH) so that it no longer functions
What is amylase?
-produced in the salivary glands and pancreas
-is a carbohydrase that breaks down starch into sugar
What is protease?
-produced in the stomach, pancreas and small intestine
-breaks down proteins into amino acids
What is lipase?
-produced in the pancreas and small intestine
-breaks down lipids into fatty acids and glycerol
What is bile?
a liquid made in the liver and stored in the gall bladder. it is alkaline to neutralise hydrochloric acid from the stomach. it also emulsifies fat to form small droplets, increasing the surface area for enzymes to act on.
What is blood made out of?
a liquid called plasma, which has three different components suspended in it: red blood cells, white blood cells and platelets
What is the function of plasma?
transports various chemical substances around the body, such as the products of digestion, hormones, antibodies, urea and carbon dioxide
Describe a red blood cell.
-contains haemoglobin, which binds to oxygen to transport it from the lungs to the tissues and cells, which need it for respiration
-do not contain a nucleus, so there is more room for haemoglobin
-very small so they can fit through the capillaries
-shaped like biconcave discs,giving them a large surface area that oxygen can quickly diffuse across
Describe a white blood cell.
-helps the body protect against infection
-can change shape, so they can squeeze out of the blood vessels into the tissues or surround and engulf microorganisms
What are platelets?
fragments of cells, which collect at wounds and trigger blood clotting